Add resolv

[lorenzleutgeb]

Description

See #4611

Sources

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI

@rustbot label +stable-nominated

[devnexen]

several things at quick glance :

• res_init is already defined for supported platforms (see src/unix/mod.rs)
• couple of definitions errors, with this change it passes for me

diff --git a/libc-test/semver/linux.txt b/libc-test/semver/linux.txt
index 86e5baa8..2260d010 100644
--- a/libc-test/semver/linux.txt
+++ b/libc-test/semver/linux.txt
@@ -4218,7 +4218,6 @@ regmatch_t
 regoff_t
 remap_file_pages
 removexattr
-res_init
 res_mkquery
 res_query
 res_querydomain
diff --git a/src/unix/linux_like/mod.rs b/src/unix/linux_like/mod.rs
index ef7426df..41e9999b 100644
--- a/src/unix/linux_like/mod.rs
+++ b/src/unix/linux_like/mod.rs
@@ -2069,8 +2069,6 @@ extern "C" {
     pub fn setdomainname(name: *const c_char, len: size_t) -> c_int;
 
     // <resolv.h>
-    #[allow(dead_code)]
-    pub fn res_init() -> c_int;
     pub fn res_query(
         dname: *const c_char,
         class: c_int,
@@ -2098,13 +2096,13 @@ extern "C" {
         dname: *const c_char,
         class: c_int,
         kind: c_int,
-        data: *mut c_char,
-        newrr: *const c_void,
+        data: *const c_uchar,
         datalen: c_int,
-        buf: *mut c_char,
+        newrr: *const c_uchar,
+        buf: *mut c_uchar,
         buflen: c_int,
     ) -> c_int;
-    pub fn res_send(msg: *const c_char, msglen: c_int, answer: *mut c_char, anslen: c_int)
+    pub fn res_send(msg: *const c_uchar, msglen: c_int, answer: *mut c_uchar, anslen: c_int)
         -> c_int;
 }

hope it helps (hopefully it will pass on android :) do not have the sdk and nothing set to check it).

[tgross35]

What exactly is the linking story here, by the way? Are the symbols always distributed with the libc binary?

[tgross35]

This shouldn't be needed

[tgross35]

This doesn't seem to match the definitions linked at #4611: those have data as const and followed by an integer

[devnexen]

also few arguments misplacements see above my comment and on linux it should be linked to libresolv.